Change DbContext connection at run-time

a bit late on this answer but I think there's a potential way to do this with a neat little extension method. As slypete (nice name :-)) says, you only need ONE class model, assuming all tables/properties are identical. This being the case, we can take advantage of the EF convention over configuration plus a few little framework calls.

Anyway, without further ado, the commented code and example usage:

the extension method class:

public static class ConnectionTools{    // all params are optional    public static void ChangeDatabase(        this DbContext source,        string initialCatalog = "",        string dataSource = "",        string userId = "",        string password = "",        bool integratedSecuity = true,        string configConnectionStringName = "")         /* this would be used if the        *  connectionString name varied from         *  the base EF class name */    {        try        {            // use the const name if it's not null, otherwise            // using the convention of connection string = EF contextname            // grab the type name and we're done            var configNameEf = string.IsNullOrEmpty(configConnectionStringName)                ? source.GetType().Name                 : configConnectionStringName;            // add a reference to System.Configuration            var entityCnxStringBuilder = new EntityConnectionStringBuilder                (System.Configuration.ConfigurationManager                    .ConnectionStrings[configNameEf].ConnectionString);            // init the sqlbuilder with the full EF connectionstring cargo            var sqlCnxStringBuilder = new SqlConnectionStringBuilder                (entityCnxStringBuilder.ProviderConnectionString);            // only populate parameters with values if added            if (!string.IsNullOrEmpty(initialCatalog))                sqlCnxStringBuilder.InitialCatalog = initialCatalog;            if (!string.IsNullOrEmpty(dataSource))                sqlCnxStringBuilder.DataSource = dataSource;            if (!string.IsNullOrEmpty(userId))                sqlCnxStringBuilder.UserID = userId;            if (!string.IsNullOrEmpty(password))                sqlCnxStringBuilder.Password = password;            // set the integrated security status            sqlCnxStringBuilder.IntegratedSecurity = integratedSecuity;            // now flip the properties that were changed            source.Database.Connection.ConnectionString                 = sqlCnxStringBuilder.ConnectionString;        }        catch (Exception ex)        {            // set log item if required        }    }}

usage:

// assumes a connectionString name in .config of ADBEntitiesvar selectedDb = new ADBEntities();// so only reference the changed properties// using the object parameters by nameselectedDb.ChangeDatabase    (        initialCatalog: "name-of-bdb-initialcatalog",        userId: "jackthelad",        password: "nosecrets",        dataSource: @".\sqlexpress" // could be ip address 100.23.45.67 etc    );

I currently use this for exactly the purpose that you mention above and thus far, it's served me very well. Hope it helps in your instance.

Pass the appropriate connection string / connection name when creating a DbContext

http://msdn.microsoft.com/en-us/library/gg679467%28v=vs.113%29.aspx

using (var context = new MyDbContext("Server=localhost;Database=dbA;...")){    return context.Users.Where(u => u.Email == "someemail@google.ca").Single();} 

var defaultString = _myContext.Database.GetDbConnection().ConnectionString;_myContext.Database.GetDbConnection().ConnectionString ="new connection" or _myContext.Database.GetDbConnection().ChangeDatabase()//your query.._myContext.Database.GetDbConnection().ConnectionString = defaultString;